Long Term Evolution (LTE) is a technology that is being standardized by Third Generation Partnership Project (3GPP) forum as part of the 4th Generation wireless network evolution. LTE is flexible on spectrum requirement point and can operate in different frequency bands. The list of flexibility requirement LTE spectrum allocations (1.25, 1.6, 2.5, 5, 10, 15 and 20 MHz) and furthermore, LTE can also operate in unpaired as well as paired spectrum. From a user equipment perspective, it is mandatory in LTE for user equipments to support 20 MHz frequency band.
As more and more MTC devices are deployed in this field, this naturally increases the reliance on Global System for Mobile Communications (GSM)/General Packet Radio Service (GPRS) networks. This will cost operators not only in terms of maintaining multiple Radio Access Technology (RATs), but it also prevents operators from reaping the maximum benefit out of their spectrum (given the non-optimal spectrum efficiency of GSM/GPRS). Because usage of high number of MTC devices, the overall resource they need for service provision may be correspondingly significant and inefficiently assigned.
Low cost LTE modems are critical for supporting and migrating M2M applications to LTE networks. The LTE baseband processing circuits and Radio Frequency (RF) components are critical components in the overall cost. RF Bill Of Material (BOM) recurring costs is not insignificant at all, it is about 4 dollars for a dual band GSM phone, 5 dollars for a tri band phone and 6 dollars for a quad band phone, as a result BOM for RF components for LTE will be much higher.
Currently approaches for achieving low cost MTC devices in LTE networks are as follows:
1) Dedicated MTC LTE Carrier:
A dedicated narrowband carrier could be used for MTC devices. The advantage of this approach is that there are no specifications impacts in this approach. The Disadvantages are that there may not be available spectrum to deploy a dedicated MTC carrier. Some eNode-Bs might not have the ability to support a narrowband carrier (e.g., as may be the case if it is necessary to split an existing carrier). This also goes against a key requirement of “Target operation of low-cost MTC devices and legacy devices on the same carrier” and use of a separate carrier for the support of low bandwidth MTC devices would be directly contradictory to this requirement.
2) Relay Node:
The possibility of using a relay node where the Un bandwidth is (evidently) the same as that of the legacy carrier, but the Uu bandwidth is a low bandwidth that is compatible with MTC devices. Although the use of relays was originally proposed from the perspective of bandwidth reduction, they might also be useful from the perspective of improving coverage for any MTC devices that have a lower transmit power capability or for single receive antenna devices. Advantages are that there are no impacts on the legacy eNode B and the potential to improve uplink and downlink coverage for cost reduced devices that have either a single receive chain or low transmit power. The disadvantages are that the deployment of extra hardware is required. Existing relay nodes would not necessarily support this functionality and may need to be upgraded or replaced. The complexity of existing relay nodes would be increased. MTC devices in the coverage area of the donor eNode-B (as opposed to a relay node) would not be supported by the low bandwidth Uu link.
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.